This research proposal aims to investigate certain specific aspects of growth at a cellular level. We plan to extend our studies of DNA polymerase activity during normal and altered growth. The influence of maternal protein restriction, uterine artery ligation and maternal diabetes on fetal growth is to be examined. The pheomena accompanying "catch-up" growth after nutritional rehabilitation are to be characterized in regard to net changes in DNA, RNA, protein and temporal patterns of DNA polymerase and thymidine uptake. The effects of nutritional alterations on adipose tissue DNA polymerase are to be assessed after the normal ontogeny has been described for this enzyme. The ultimate goal is to gain additional information about the mechanisms which control growth which can be eventually applied clinically to disordered growth in children.